__init__(self,
taskmaster)(Constructor)

The taskmaster's next_task() method should return the next task
that needs to be executed, or None if there are no more tasks. The
taskmaster's executed() method will be called for each task when it
is successfully executed or failed() will be called if it failed to
execute (e.g. execute() raised an exception).

Overrides:
object.__init__

start(self)

Start the job. This will begin pulling tasks from the taskmaster
and executing them, and return when there are no more tasks. If a task
fails to execute (i.e. execute() raises an exception), then the job will
stop.